This invention concerns improved lubricating compositions having multifunctional properties. Another aspect of the invention relates to addition compositions which impart antiwear and antiscuffing properties to lubricating compositions and improve resistance to oxidation and extreme pressure.
The useful life of nearly all automotive and industrial engines is limited by the decrease in size of important engine parts due to wear. This occurs by removal of metal from surfaces by mechanical or chemical attack. To minimize friction and wear, various antiwear additives have been added to lubricants to produce a protective surface film on the metal parts. However, the antiwear lubricants may exhibit other unsatisfactory lubricating characteristics such as deterioration due to oxidation under high temperature conditions and subsequently may have to be formulated with supplemental lubricating additives to prevent such detremental effects.
It is known that sulfurized molybdenum dihydrocarbyldithiocarbamates possess antiwear properties as well as other desirable lubricating characteristics as disclosed in U.S. Pat. No. 3,356,702 granted Dec. 5, 1967; U.S. Pat. No. 3,509,051 granted Apr. 28, 1970; U.S. Pat. No. 4,098,705 granted July 4, 1978.
Surprisingly, it has been now discovered that sulfurized molybdenum dialkyldithiocarbamates produce a synergistic antiwear effect in combination with certain organic sulfur compounds. Moreover, these combinations possess excellent oxidation inhibiting and extreme pressure properties when incorporated into lubricants.